1. Technical Field of the Invention
The invention concerns a safety function element to influence or control fluid mediums in a line, in particular a double-walled safety line whose walls are spaced at a distance to each other through a hollow space, the element being provided with a housing formed by walls and having as well flanges by means of which it can be connected tightly to the line.
2. Description of the Prior Art
In piping systems in many cases easily inflammable or explosive liquids as well as gases and products that endanger the water and are injurious to health and the environment are transported. Because an uncontrolled release of the transported medium would result in significant damage and risks, for preventive purposes, the use of double-walled safety lines is known, whose walls are spaced at a distance to each other through a hollow space. In this way not only is protection against an escape of the medium directly improved, it is also possible to connect the hollow space to a measuring device to check its contents, for example, a detection device for specific gases or a pressure gauge. Therefore a leak report and subsequent cut-off of transport through the line is effected as soon as the medium enters the hollow space so that the risk of a spillage affecting the environment is completely ruled out.
As a rule, lines are provided with a multitude of function elements. Examples are non-return or shutoff valves, slide valves, pumps or flow meters, which are connected respectively, via flanges, to the line pipes which may comprise rigid or flexible material. In the region of the function elements no suitable measures are known to provide protection against the medium leaking. On the one hand, this has the consequence that operationally the function elements represent a considerable source of danger with leakages occurring with above average frequency compared with the line. On the other hand, during the construction of a line it means significantly higher expenditure because permanent access must be guaranteed, also by statute, even if the line is laid underground, to the function elements. Therefore, in the state-of-the-art, the function element is fitted either in a shaft or an underground loop so that significant extra costs are the disadvantageous consequence. In addition to the function elements themselves, the flanges, to which they are connected, for example, by means of bolts to fit tightly with the adjacent line, represent further regions in which leaks occur especially frequently.